Talk It Over

Sometimes you have to throw your bread out. It gets mold growing on it. Some bread molds look green. Some are black, white, or orange. You can use bread molds as a convenient way to test how well hand sanitizers and soaps work against microscopic life forms like molds.

Get

• 8 ziptop plastic bags, sandwich size
• Labels and pen
• Latex gloves
• 4 slices of bread, without preservatives or organic works best
• Toaster
• Knife
• Cookie sheet
• Spray bottle of water
• 1 soap and 1 hand sanitizer to test
• Measuring teaspoon
• Camera or drawing materials

Go

1. Label the bags as shown in the table:

    

   Bag Number	Bread	Treatment
   1	Not toasted	None
   2	Not toasted	Water spray only
   3	Not toasted	Soap spray
   4	Not toasted	Hand sanitizer spray
   5	Toasted	None
   6	Toasted	Water spray only
   7	Toasted	Soap spray
   8	Toasted	Hand sanitizer spray

2. Wear the gloves as you set up this experiment. Toast two of the bread slices.
3. Get an adult to cut all the bread slices in half for you, like this:

   

   You have four pieces that are toasted and four pieces that are not toasted. Put them on the cookie sheet.

4. Put a piece that is not toasted in bag 1. Seal. Put a toasted piece in bag 5 and seal.
5. Put water in the spray bottle. Spray an untoasted and a toasted piece lightly with a fine mist of water.Put them in bags 2 and 6. Seal the bags.
6. Add 1 teaspoon of the hand soap to the water in the spray bottle. Shake to mix thoroughly. Spray as you did in step 5 to add pieces to bags 3 and 7.
7. Empty the spray bottle and rinse it several times. Add fresh water and 1 teaspoon of hand sanitizer. Shake to mix thoroughly. Spray as you did in step 5 to make the last 2 slices for bags 4 and 8.
8. Put all the bags, sprayed side up, on the cookie sheet. Place them in a warm, dark place. Every day, observe the bread in the bags. Take careful notes. If you see mold colonies (colored or fuzzy circles) on the bread, count them. Take or draw pictures of what you see in the bags.

Stay Safe

Do not open the bags after the experiment begins and discard them safely when it is over. Dangerous microbes are not likely to grow inside the bags, but it is possible.

Go Easy

Set up only bags 1–4, using only untoasted bread.

Go Far

Extend your project by investigating other variables that could affect the kinds of molds that grow on the bread and their growth rate. You might try varying temperature, humidity, light/dark, or the kind of container the bread is kept in. Do some research to identify the kinds of fungi (the scientific name for molds) that commonly grow on bread, and learn to identify them. If you have a dissecting microscope—or if you can borrow one from you school—you can examine the molds on your bread and draw pictures of their structure. One common one, called Rhizopus, looks like this:

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